1. Field of the Invention
This invention relates to electrical power circuit and more particularly to a voltage compensation circuit for proving an elevated output AC voltage upon an undervolt input AC voltage condition.
2. Description of the Related Art
It is well known in the art that many electrical devices may be damaged by a low voltage alternating current AC power input. Among the electrical devices that are most sensitive to a low voltage input include electric motors that power various devices such as an air conditioning compressor.
Various devices have been proposed by the prior art to compensate for a low voltage alternating current AC power source. The following United States patents and patent applications a representative of the efforts of the prior art to provide an electrical device for compensating for a low voltage alternating current power source.
U.S. Pat. No. 2,063,693 to McCarty discloses an alternating current circuit comprising a transformer having a plurality of windings including a series winding in said alternating current circuit and an exciting winding. A negative current characteristic impedance is connected across one of the windings of said transformer other than said series winding. A circuit controller selectively connects said exciting winding across said alternating current circuit and disconnecting it.
U.S. Pat. No. 4,131,927 to Tsuchiya, et al. discloses a circuit for preventing a current surge normally associated with the initial application of a nominal A.C. current to an inductive load. The surge is prevented by preventing the magnetic core of the inductive load from being driven into saturation. Initially, the current is half wave rectified and amplitude limited. The amplitude limitation insures that the core will not be driven into saturation. A voltage detector connected across the inductive load senses only the counter E.M.F. of a polarity opposite to the polarity of the half wave current. When the sensed voltage reaches a predetermined value, a direct connection is provided between the A.C. supply and the inductive load, bypassing the half wave rectifier and the amplitude limiter.
U.S. Pat. No. 4,716,357 to Cooper discloses an apparatus for AC line voltage regulation has an input port for connection to an AC source, an output port for connection to a load, and a transformer assembly connected between the input and output ports. The transformer assembly comprises a buck/boost winding and a primary winding wound about a common transformer core, and a switch arrangement for controlling the connection of the primary winding in circuit with the buck/boost winding. Switch actuators control switches responsive to a voltage sensor assembly to connect the primary winding in either of two possible conditions when the voltage is outside predetermined limits. The transformer assembly comprises either a step down transformer for reducing or bucking the output voltage or a step up transformer for compensation the output voltage according to the condition of the switch arrangement. The primary may comprise separate windings controlled by the switching assembly for connection in different configurations.
U.S. Pat. No. 4,853,608 to Schrade discloses an AC voltage regulator includes a transformer arrangement having a plurality of taps so that an input line voltage is passed to an output line with the output line voltage being determined by the nominal value of the input line voltage together with an amount contributed by the transformer. A network of relays switch the device that act as a polarity reversal switch so that the voltage generated by the transformer is either added or subtracted to the nominal voltage. Further relays used in two series control the selection of the transformer tap. A transient suppression circuit uses a triac and resistor to communicate current from the input line to the output line with the triac gated into conduction on breaking of a relay contact. A comparator measures the input line voltage using a plurality of op-amps in series with the outputs passing through a logic circuit to control the relays.
U.S. Pat. No. 4,897,522 to Bilczo et al. discloses a control circuit is provided for the output of a high frequency inverter of the type having an output transformer with a core, primary windings and a secondary winding with two sections for creating a first secondary current pulse of electrical current in one section when the primary windings magnetizes the core and a second secondary current pulse in the other of the secondary sections when the primary windings remagnetizes the core. By alternating switch means for passing current through the primaries to magnetize and remagnetize the core at a preselected rate the output current pulses are provided by the two sections of secondary windings. The control circuit of the present invention involves a modification of the output transformer secondary stage. A first auxiliary winding is connected to one of the secondary sections to create an auxiliary current pulse as the core of the transformer is magnetized. A means is then employed for limiting this auxiliary current pulse and for adding the limited auxiliary current pulse to the first secondary pulse created by the secondary section to which the auxiliary winding is connected. In a like manner, a second auxiliary winding is connected to the other of the secondary sections to create a second auxiliary current pulse as the core is remagnetized. Means are provided for limiting the second auxiliary current pulse and for adding the second auxiliary current pulse to the second secondary current pulse from the secondary winding. Addition of limited current pulses to secondary current pulses created by the inverter provides a maximum output voltage that is higher than the maximum output voltage normally available while conserving primary current under higher output current conditions.
U.S. Pat. No. 5,450,305 to Boys et al. discloses a resonant power supply produces a varying magnetic field from a resonant inductor. Two active switches drive, but remain outside, a resonant circuit, also including resonant capacitor. A phase-splitting transformer provides, via a decoupling inductor, one connection for a power supply; the return is through the active switches, which are either off or are from time to time driven alternately by the controller so as to maintain the resonant current in the resonant circuit. Applications include induction heating and induction hobs for cooking, and also a power source for inductively powered vehicles (or other inductively powered devices) adjacent to an inductive pathway.
U.S. Pat. No. 5,461,300 to Kappenman discloses a dynamic phase angle regulator for enhancing the transient stability of a three-phase AC power system includes a controller, a switching assembly of thyristor switches, and a single transformer coupled to a power line. The transformer includes a balanced three-phase configuration of exciting windings coupled to nodes at each phase of a three-phase transmission system. Each phase of the transformer further includes a pair of regulating windings electrically coupled to the node and magnetically coupled to a corresponding exciting winding. Each exciting winding induces a voltage on the corresponding pair of regulating windings. To provide a selected phase shift, the controller actuates the switching assembly in response to a transient event to add a voltage induced on the regulating windings to the line voltage. A method is also provided for regulating the phase angle in a polyphase power transmission system.
U.S. Pat. No. 5,581,173 to Yalla et al. discloses a micro controller based tap-changer controller including apparatus for keeping track of an electrically closed tap position and for automatically changing the tap setting of load tap-changing transformers and regulators; the tap-changer controller further utilizes the “keep-track” tap position to calculate the source voltage of the regulator for reverse power operations; and, a method for paralleling tap-changing transformers and regulators utilizing the circulating current of the units.
U.S. Pat. No. 5,712,554 to Lace discloses a voltage compensation device for a two-conductor A.C. power line supplying one or more air conditioners, a telephone system or other telecommunication system, or some other utilization system that requires an input voltage within a given range. The device includes a transformer having electromagnetically coupled primary and secondary windings with the primary and secondary each connected to at least one output terminal. One winding is connected to add voltage to the A.C. line voltage when the line voltage drops below a given low voltage threshold, and in bucking (subtractive) relation when the A.C. line voltage exceeds a given high voltage threshold. When the A.C. line voltage is in the range required by the utilization system, the one winding is effectively shorted out or otherwise disconnected. A sensor for the line voltage actuates one or more relays connected to the transformer to effect the desired compensation action. The voltage compensation device may handle either under-voltage conditions or over-voltage conditions, or both. In one embodiment the one winding is split to afford two levels of voltage compensation both for under-voltage and over-voltage conditions.
U.S. Pat. No. 5,883,503 to Lace discloses a voltage compensation system for an A.C. power line supplying one or more air conditioners, a telephone system or other telecommunication system, a battery charger, or some other utilization system that should have an input voltage within a given normal range. The voltage compensation system includes a transformer unit containing a transformer having at least two windings coupled electromagnetically by a transformer core; one of those windings preferably is in two segments that are connectable in series or in parallel. One winding is connected to an input terminal and to an output terminal. The other winding adds to the A.C. line voltage when the line voltage drops below a low voltage threshold and/or subtracts from the line voltage when the A.C. line voltage exceeds a high voltage threshold. If the A.C. line voltage is in the range required by the utilization system, the other transformer winding is effectively shorted out or otherwise disconnected. In automated versions, a line voltage sensor actuates a switching circuit to effect the desired compensation action. The voltage compensation system may handle under-voltage conditions, over-voltage conditions, or both. For chronic under-voltage or over-voltage conditions, direct winding connections may be employed instead of relays.
U.S. Pat. No. 5,990,667 to Degeneff et al. discloses a regulator is provided for establishing asymmetrical voltage increase/decrease capability between an input node and an output node for enhanced regulation of either voltage sag or voltage swell within a utility system. The regulator includes an autotransformer having an input tap coupled to the input node of the regulator and an output tap coupled to the output node. The regulator further includes an electronic tap changer system coupled to the winding of the autotransformer. Together, the autotransformer and the electronic tap changer system provide the regulator with its asymmetrical voltage increase/decrease capability between the input node and the output node thereof. The regulator can be configured for voltage increase only, voltage decrease only, or both, provided an asymmetrical voltage increase/decrease capability.
U.S. Pat. No. 6,087,818 to Hughes discloses a voltage booster device for increasing the voltage level of power received by a recreational vehicle (RV) from a separate 120-volt power source includes an electrical box, a power cord and female outlet on the box, and an encapsulated transformer within the box. The transformer (e.g., an autotransformer) is adapted to increase the actual voltage level of the separate 120-volt power source a predetermined amount. A relay is provided for switching the transformer, the power cord, and the female outlet between (i) a first circuit configuration that couples power from the power cord to the female outlet via the transformer so that the transformer increases the voltage level by the predetermined amount, and (ii) a second circuit configuration that bypasses the transformer so that the transformer does not increase the voltage level by the predetermined amount. A control circuit controls the relay so that (i) the relay switches to the first circuit configuration when the actual voltage of the separate 120-volt power source falls below a predetermined first threshold level, and (ii) the relay switches to the second circuit configuration when the actual voltage rises above a predetermined second threshold level. One embodiment includes a mounting plate with a rounded end that functions as a handle, and a case hardened steel loop that receives a security chain.
U.S. Pat. No. 6,100,673 to Bair, III et al. discloses a voltage control apparatus (10) selectively boosts or bucks an input voltage in order to provide a selected output voltage. In the preferred embodiment, the apparatus includes a transformer (T1) having a plurality of secondary voltages presented at respective output connections (A-E), a connection circuit (12) having actuatable connection elements (R1-R6) to interconnect selected ones of the output connections, and a control circuit (14) operable to sense the input voltage at the primary of the transformer (T1) and to activate selected ones of the connection elements to produce a selected output voltage for delivery to a load. The preferred connection elements include electromechanical relays.
U.S. Pat. No. 6,137,277 to Rajda et al. discloses a static voltage regulator consists of a booster transformer, a regulator transformer, an electronic switching system and a control system. The booster transformer includes a booster primary winding and a booster secondary winding. The booster secondary is provided in series with the input and output terminals of the regulator so as to produce an output voltage. The regulator transformer includes a regulator primary winding and a regulator secondary winding. The regulator primary is electrically coupled to the output. The electronic switching system is coupled between the regulator secondary and the booster primary for providing a voltage to the booster primary. The control system includes a voltage sensor for sensing a voltage at the input, and a gating system coupled to the switching system for switching the output voltage in response to changes in the sensed input voltage. The voltage regulator also includes a notch filter coupled to the booster transformer for reducing transients induced in the booster transformer when the output voltage is switched.
U.S. Pat. No. 6,538,909 to Goodarzi et al discloses a universal power converter for generating a regulated voltage, current or power with a large input voltage range. The power converter has a voltage boost function configured to boost the rectified input voltage and provide power factor correction. The power converter also includes a voltage chop function to chop the boosted voltage to form an AC voltage. The power converter further includes at least one relay in electrical communication with the AC voltage and a transformer. The primary winding has at least two inputs operative to selectively vary the voltage generated on a secondary winding thereof selected by the relay. Accordingly, the power converter can generate different voltages at the output based upon the position of the relay and the boosted voltage. The power converter provides maximum power operation at a wide output voltage range, maximizing the charging energy.
U.S. Pat. No. 7,177,168 to Toyomura et al. discloses an AC module makers must prepare two types of AC modules for the 100-V and 200-V outputs only for domestic supply. For foreign countries, the makers must manufacture AC modules compatible with more system voltages. To solve these problems, the control circuit of an AC module controls the operation of an inverter circuit and/or the transformation ratio of a transforming circuit, and ON/OFF-controls a switch on the basis of the system voltage and connection state of an electric power system.
U.S. Patent application 2002/0044468 to Goodarzi et al. discloses universal power converter for generating a regulated voltage, current or power with a large input voltage range. The power converter has a voltage boost function configured to boost the rectified input voltage and provide power factor correction. The power converter also includes a voltage chop function to chop the boosted voltage to form an AC voltage. The power converter further includes at least one relay in electrical communication with the AC voltage and a transformer. The primary winding has at least two inputs operative to selectively vary the voltage generated on a secondary winding thereof selected by the relay. Accordingly, the power converter can generate different voltages at the output based upon the position of the relay and the boosted voltage. The power converter provides maximum power operation at a wide output voltage range, maximizing the charging energy.
U.S. Patent application 2002/0044473 to Toyomura et al. discloses a control circuit of an AC module having an inverter circuit and/or the transformation ratio of a transforming circuit for switching between domestic supply voltages and for foreign supply voltages.
U.S. Patent application 2004/0151011 to Toyomura et al. discloses a control circuit of an AC module having an inverter circuit and/or the transformation ratio of a transforming circuit for switching between domestic supply voltages and for foreign supply voltages.
U.S. Patent application 2008/0012626 to Kimura et al. discloses a booster circuit comprising an input terminal; an output terminal; a common terminal; a transformation unit including first, the second, and the third windings, the windings wound in the same direction and connected in series. A first rectifier unit is provided between the input terminal and a connection point of the first and the second windings; a second rectifier unit provided between the input terminal and a connection point of the second and the third windings. A first switching unit is provided between one end of the transformation unit and the common terminal. A second switching unit is provided between other end of the transformation unit and the common terminal. A third rectifier unit is provided between a connection point of one end of the transformation unit and the first switching element and the output terminal. A fourth rectifier unit is provided between a connection point of other end of the transformation unit and the second switching element and the output terminal. The first winding and the third winding have the approximately same number of turns and the first switching element and the second switching element open and close alternately to each other in response to a pair of control signals. Thereby, it is possible to provide a booster circuit that is capable of generating an output voltage, which is more than twice as high as an input voltage, and can be reduced in the size and the weight.
Although the aforementioned discloses have contributed to the art, it is an object of the present invention to provide a voltage compensation circuit that provides a further significant improvement in the electrical art.
Another object of this invention is to provide a voltage compensation circuit that incorporates an autotransformer for providing an elevated output AC voltage output upon an under voltage input AC voltage.
Another object of this invention is to provide a voltage compensation circuit that is applicable to a wide variety of voltage compensation uses.
Another object of this invention is to provide a voltage compensation circuit that is lighter and more cost effective than the voltage compensation circuit of the prior art.
Another object of this invention is to provide a voltage compensation circuit that requires a reduced number of electrical components.
Another object of this invention is to provide a voltage compensation circuit incorporating an arc suppression circuit.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by modifying the invention within the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment of the invention.